TGFB1 and pulmonary fibrosis: Moreover, the glycolytic enzyme PKM2 tetramer enhances TGF-β1 signaling through direct binding of Smad7 to its MH2 structural domain, which interferes with the interaction between Smad7 and the TGF-β type I receptor (TβR1), reduces TβR1 ubiquitination, stabilizes TβR1, and affects lung fibrosis [128].